DOCSLIB.ORG

STIM Proteins: an Ever-Expanding Family

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
STIM Proteins: an Ever-Expanding Family International Journal of Molecular Sciences Review STIM Proteins: An Ever-Expanding Family Herwig Grabmayr , Christoph Romanin * and Marc Fahrner * Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz, Austria; [email protected] * Correspondence: [email protected] (C.R.); [email protected] (M.F.) Abstract: Stromal interaction molecules (STIM) are a distinct class of ubiquitously expressed single- pass transmembrane proteins in the endoplasmic reticulum (ER) membrane. Together with Orai ion channels in the plasma membrane (PM), they form the molecular basis of the calcium release- activated calcium (CRAC) channel. An intracellular signaling pathway known as store-operated calcium entry (SOCE) is critically dependent on the CRAC channel. The SOCE pathway is activated by the ligand-induced depletion of the ER calcium store. STIM proteins, acting as calcium sensors, subsequently sense this depletion and activate Orai ion channels via direct physical interaction to allow the influx of calcium ions for store refilling and downstream signaling processes. This review article is dedicated to the latest advances in the field of STIM proteins. New results of ongoing investigations based on the recently published functional data as well as structural data from nuclear magnetic resonance (NMR) spectroscopy and molecular dynamics (MD) simulations are reported and complemented with a discussion of the latest developments in the research of STIM protein isoforms and their differential functions in regulating SOCE. Keywords: STIM1; STIM2; isoforms; Orai; CRAC; SOCE; CC1; NMR; structure; simulation 1. Introduction Chemical elements in their ionic form are indispensable factors for the correct function Citation: Grabmayr, H.; Romanin, C.; of vital cells and organisms. Among the various ions that have been selected in the course Fahrner, M. STIM Proteins: An of evolution to be involved in living organisms, calcium (Ca2+) occupies a special place. Ever-Expanding Family. Int. J. Mol. Besides the enormous amounts found in bones and teeth, calcium plays an outstanding Sci. 2021, 22, 378. https://doi.org/ role as a second messenger in every cell [1–4]. In a resting cell, calcium is present in a very 10.3390/ijms22010378 low cytosolic concentration. For intracellular calcium-dependent signal transduction, an Received: 5 December 2020 increase of the cytosolic calcium concentration is necessary. This is achieved by calcium Accepted: 26 December 2020 influx from the extracellular space or by depletion of the intracellular calcium store in the Published: 31 December 2020 endoplasmic reticulum (ER) [4]. Among the different calcium-selective transmembrane proteins, the pathway of store-operated calcium entry (SOCE) plays an important role. Publisher’s Note: MDPI stays neu- Two key proteins, stromal interaction molecule (STIM) and Orai, form the calcium release- tral with regard to jurisdictional clai- activated calcium (CRAC) channel system that mediates SOCE and is responsible for ms in published maps and institutio- regulated calcium influx in many cell types [5–8]. Orai is the calcium-selective channel in nal affiliations. the plasma membrane (PM) and STIM is the calcium sensor in the ER membrane. Ligand binding to the extracellular surface of the cell leads to cytosolic activation of phospholipase C (PLC), which in turn cleaves the head group of a specific phospholipid to form cytosolic inositol trisphosphate (IP3) and membrane-bound diacylglycerol (DAG). IP3 diffuses Copyright: © 2020 by the authors. Li- throughout the cytosol to IP3 receptors in the ER membrane and elicits depletion of the censee MDPI, Basel, Switzerland. store. As a result, the ER luminal calcium concentration decreases dramatically [2,4,9] This article is an open access article This is the step that represents the STIM-activating signal [10–13]. STIM has, among other distributed under the terms and con- ditions of the Creative Commons At- elements, an EF hand in its ER luminal N-terminus with which the calcium concentration in tribution (CC BY) license (https:// the ER can be sensed [14,15]. Lowering the ER calcium concentration results in dissociation creativecommons.org/licenses/by/ of calcium from the STIM EF hand and thus in a conformational change of the STIM 4.0/). N-terminus [10]. The signal propagates across the transmembrane (TM) domain to the Int. J. Mol. Sci. 2021, 22, 378. https://doi.org/10.3390/ijms22010378 https://www.mdpi.com/journal/ijms Int. J. Mol. Sci. 2021, 22, 378 2 of 18 cytosolic C-terminus of STIM [16]. A cascade of conformational changes occurs at the STIM C-terminus, resulting in oligomerization and spatial extension of the protein [16–22]. The extended STIM protein translocates to the cell periphery and interacts directly with the PM-resident protein Orai [8,23,24]. The physical coupling to Orai occurs mainly at its C-terminus; however, interactions with Orai loop2 and N-terminus are also involved in the correct gating of the channel [25,26]. In its monomeric form, Orai has 4 TM domains, a cytosolic N- and C-terminus, and a cytosolic loop2 between TM2 and TM3. Six Orai monomers form the functional hexameric Orai channel [27]. Six TM1 domains constitute the calcium-selective channel pore, which is separated from the hydrophobic milieu of the PM and from the TM4 domains by a ring consisting of TM2 and TM3. The Orai N-terminus merges into the TM1 and the C-terminus merges into the TM4 [8,25,27]. The importance of SOCE for physiological cytosolic calcium homeostasis and the calcium-dependent function of critical cell-biological processes is underlined by several gain- (GoF) and loss-of-function (LoF) mutations within STIM and Orai. GoF mutations raise the intracellular calcium concentration by eliciting constitutive CRAC channel activation as well as SOCE. This leads to a clinical continuum including disease phenotypes termed York platelet syndrome, Stormorken syndrome, and tubular aggregate myopathy. Pathological manifestations thereby include (but are not limited to) myopathy, thrombocytopenia, miosis, ichthyosis, and dyslexia. In contrast, LoF mutations abolish CRAC channel activation. The absence of SOCE results in severe combined immunodeficiency, autoimmunity, ectodermal dysplasia, and muscular hypotonia [28,29]. In this review, we focus on the growing family of STIM isoforms, which are specifi- cally expressed in various cell types. Key regulatory domains of the protein involved in stabilizing the STIM resting state and domains involved in protein activation are described. The focus is on competitive interactions of cytosolic domains of STIM. The recently pub- lished functional data as well as structural data from nuclear magnetic resonance (NMR) spectroscopy and molecular dynamics (MD) simulations have been essential in advancing and complementing the characterization of STIM [15,21,22,30]. Moreover, we report results of ongoing functional investigations that are based on these novel NMR data. 2. STIM Proteins STIM is a dimeric type I single-pass TM protein which is mainly anchored in the ER membrane [5,31–33] and to some extent in acidic stores [34] as well as the PM [35–37]. It generally consists of an N-terminal ER luminal portion and a larger C-terminal portion in the cytosol that are connected by a TM domain (Figure1)[ 8]. STIM possesses two main functions: on the one hand, it is a precise sensor of the calcium concentration within the ER lumen; on the other hand, it couples to and gates calcium-selective Orai channels in the plasma membrane [6,7]. In order to perform these two tasks, STIM is equipped with several specialized domains spread across its N- and C-terminal portions [7,38]. There are two homologous STIM proteins called STIM1 and STIM2, each having different isoforms that have been characterized since the discovery of the protein family. For STIM1, these include STIM1 Long (STIM1L) and the recently discovered STIM1A (Figure1a) [ 39,40]. Two studies by Miederer et al. and Rana et al. in 2015 revealed a total of three STIM2 isoforms: STIM2.1 (or STIM2β), STIM2.2 (or STIM2α), and STIM2.3 (Figure1b) [ 41,42]. In this nomenclature, the conventional isoform of STIM2 is termed STIM2.2 and will be used hereafter. All isoforms will be discussed in detail after a comprehensive introduction to STIM proteins that includes the latest developments in the field and a brief report of ongoing functional investigations. Int. J. Mol. Sci. 2021, 22, 378 3 of 18 Figure 1. Domain structure of stromal interaction molecule (STIM) proteins. (a) Primary structure of STIM1 and its isoforms STIM1 Long (STIM1L) and STIM1A. Functionally relevant domains within the endoplasmic reticulum (ER) luminal portion include the canonical (cEF) and noncanonical (nEF) EF hands as well as the sterile alpha motif (SAM). Downstream of the transmembrane domain (TM), the cytosolic portion contains three coiled coil (CC) domains commonly known as CC1, CC2, and CC3 with CC1 being further subdivided into α1, α2, and α3. The C-terminal fragment spanning all three CC domains is termed Orai-activating small fragment (OASF). Another fragment comprising CC2 and CC3 is named CRAC-activating domain (CAD) or STIM-Orai-activating region (SOAR). Further C-terminal domains include the inactivation domain (ID or ID-STIM), the microtubule end-binding domain (EB), and the polybasic domain (PBD) at the outermost C-terminus. STIM1L and STIM1A feature the same general structure but each harbor an additional C-terminal domain inserted downstream of the ID domain by alternative splicing. STIM1L thereby includes an actin-binding domain (ABD) while STIM1A possesses an insert designated as domain A. (b) Primary structure of STIM2.2/STIM2α and its isoforms STIM2.1/STIM2β and STIM2.3. For reasons of simplicity, the 87 amino acid N-terminal signal peptide insertion of STIM2.2 and its isoforms was omitted from this display [43–45]. Due to the high degree of similarity between STIM1 and STIM2.2, their functional domains are essentially equivalent. Alternative splicing leads to inclusion of a small 8 amino acid insert (VAASYLIQ) within the CC2 domain of STIM2.1 and to an upstream end of translation in case of STIM2.3, shortening the protein by 148 amino acids.
Load more

Recommended publications
  • Report STIM1 Is a Calcium Sensor Specialized for Digital Signaling
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Elsevier - Publisher Connector Current Biology 19, 1724–1729, November 3, 2009 ª2009 Elsevier Ltd All rights reserved DOI 10.1016/j.cub.2009.08.022 Report STIM1 Is a Calcium Sensor Specialized for Digital Signaling Gary S. Bird,1 Sung-Yong Hwang,1 Jeremy T. Smyth,1 by immunoblot, we saw no difference in Orai1 levels between Miwako Fukushima,1 Rebecca R. Boyles,1 cells transfected with 0.5 mg cDNA/well and those transfected and James W. Putney, Jr.1,* with 2.0 mg cDNA/well (not shown). 1Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, National Institutes of Health, Effect of STIM2 Expression and Knockdown on Calcium Department of Health and Human Services, P. O. Box 12233, Oscillations Research Triangle Park, North Carolina 27709, USA Activation of HEK293 cells with low concentrations of the PLC- linked agonist methacholine (MeCh) results in repetitive cyto- plasmic calcium transients, or oscillations. An underlying entry Summary of Ca2+ maintains these oscillations, and it has been sug- gested that this entry could be activated by arachidonic acid When cells are activated by calcium-mobilizing agonists at [8]. However, more recent work demonstrated that the entry low, physiological concentrations, the resulting calcium associated with oscillations in HEK293 cells is SOCE [2, 9]. signals generally take the form of repetitive regenerative Thus, maintenance of MeCh-induced calcium oscillations discharges of stored calcium, termed calcium oscillations depends on SOCE but involves minimal depletion of ER cal- [1].
    [Show full text]
  • Association of the IP3R to STIM1 Provides a Reduced Intraluminal
    www.nature.com/scientificreports OPEN Association of the IP3R to STIM1 provides a reduced intraluminal calcium microenvironment, Received: 15 March 2018 Accepted: 15 May 2018 resulting in enhanced store- Published: xx xx xxxx operated calcium entry Alicia Sampieri1, Karla Santoyo1, Alexander Asanov2 & Luis Vaca 1 The involvement of inositol trisphosphate receptor (IP3R) in modulating store-operated calcium entry (SOCE) was established many years ago. Nevertheless, the molecular mechanism responsible for this observation has not been elucidated to this date. In the present study we show that IP3R associates to STIM1 upon depletion of the endoplasmic reticulum (ER) by activation of the inositol trisphosphate signaling cascade via G-protein coupled receptors. IP3R-STIM1 association results in enhanced STIM1 puncta formation and larger Orai-mediated whole-cell currents as well as increased calcium infux. Depleting the ER with a calcium ATPase inhibitor (thapsigargin, TG) does not induce IP3R-STIM1 association, indicating that this association requires an active IP3R. The IP3R-STIM1 association is only observed after IP3R activation, as evidenced by FRET experiments and co-immunoprecipitation assays. ER intraluminal calcium measurements using Mag-Fluo-4 showed enhanced calcium depletion when IP3R is overexpressed. A STIM1-GCaMP fusion protein indicates that STIM1 detects lower calcium concentrations near its EF-hand domain when IP3R is overexpressed when compared with the fuorescence reported by a GCaMP homogenously distributed in the ER lumen (ER-GCaMP). All these data together strongly suggest that activation of inositol trisphosphate signaling cascade induces the formation of the IP3R-STIM1 complex. The activated IP3R provides a reduced intraluminal calcium microenvironment near STIM1, resulting in enhanced activation of Orai currents and SOCE.
    [Show full text]
  • Generierung Und Charakterisierung Von Stromal Interaction Molecule 2 (STIM2)- Defizienten Mäusen
    Julius-Maximilians Universität Würzburg Generierung und Charakterisierung von Stromal Interaction Molecule 2 (STIM2)- defizienten Mäusen Generation and Characterization of Stromal Interaction Molecule 2 (STIM2)-deficient Mice Doctoral thesis for a doctoral degree at the Graduate School of Life Sciences, Section Biomedicine submitted by Alejandro Berna Erro from Alicante, Spain Würzburg, 2009 Submitted on: …………………………………………………………..…….. Office stamp Members of the Promotionskomitee: Chairperson: Prof. Dr. Thomas Hünig Primary Supervisor: Prof. Dr. Bernhard Nieswandt Supervisor (Second): Prof. Dr. Thomas Dandekar Supervisor (Third): Prof. Dr. Ulrich Walter Date of Public Defence: …………………………………………….………… Date of Receipt of Certificates: ………………………………………………. PERSONAL DEDICATION The fact that I am here writing this thesis is the result of a great effort done by other people, long time ago, that has nothing to be with research. I would like to dedicate this work to them: To my most beloved people: My parents Rafael Berna and Juana Maria Erro. They emigrated to France and learned what is working hard. They worked in the mountains under the stars, in the forests and agriculture fields. They have glamorized many dirty floors and offices. They faced many barriers and many different works to seek for a prosper times. They helped and they have been helped many times by nice people. They transmitted me their life values. I would like to include my parents as the additional formal authors of this thesis, doctors honoris causa of the other life sciences. My sister Ana Cristina and her little family: Because is MY sister and a very nice person, what else I could say. Also to her daughters, my couple little nieces Claudia and Abril, that will become great persons in the future, for pride of my sister.
    [Show full text]
  • Na+ Influx Via Orai1 Inhibits Intracellular ATP-Induced Mtorc2 Signaling to Disrupt CD4 T Cell Gene Expression and Differentiation." Elife.6
    Washington University School of Medicine Digital Commons@Becker Open Access Publications 2017 Na+ influx via Orai1 inhibits intracellular ATP- induced mTORC2 signaling to disrupt CD4 T cell gene expression and differentiation Yong Miao Washington University School of Medicine in St. Louis Jaya Bhushan Washington University School of Medicine in St. Louis Adish Dani Washington University School of Medicine in St. Louis Monika Vig Washington University School of Medicine in St. Louis Follow this and additional works at: https://digitalcommons.wustl.edu/open_access_pubs Recommended Citation Miao, Yong; Bhushan, Jaya; Dani, Adish; and Vig, Monika, ,"Na+ influx via Orai1 inhibits intracellular ATP-induced mTORC2 signaling to disrupt CD4 T cell gene expression and differentiation." Elife.6,. e25155. (2017). https://digitalcommons.wustl.edu/open_access_pubs/6064 This Open Access Publication is brought to you for free and open access by Digital Commons@Becker. It has been accepted for inclusion in Open Access Publications by an authorized administrator of Digital Commons@Becker. For more information, please contact [email protected]. RESEARCH ARTICLE Na+ influx via Orai1 inhibits intracellular ATP-induced mTORC2 signaling to disrupt CD4 T cell gene expression and differentiation Yong Miao1, Jaya Bhushan1, Adish Dani1,2, Monika Vig1* 1Department of Pathology and Immunology, Washington University School of Medicine, St Louis, United States; 2Hope Center for Neurological Disorders, Washington University School of Medicine, St Louis, United States Abstract T cell effector functions require sustained calcium influx. However, the signaling and phenotypic consequences of non-specific sodium permeation via calcium channels remain unknown. a-SNAP is a crucial component of Orai1 channels, and its depletion disrupts the functional assembly of Orai1 multimers.
    [Show full text]
  • KRAP Tethers IP3 Receptors to Actin and Licenses Them to Evoke Cytosolic Ca2+ Signals ✉ ✉ Nagendra Babu Thillaiappan 1,2 , Holly A
    ARTICLE https://doi.org/10.1038/s41467-021-24739-9 OPEN KRAP tethers IP3 receptors to actin and licenses them to evoke cytosolic Ca2+ signals ✉ ✉ Nagendra Babu Thillaiappan 1,2 , Holly A. Smith1, Peace Atakpa-Adaji1 & Colin W. Taylor 1 2+ 2+ Regulation of IP3 receptors (IP3Rs) by IP3 and Ca allows regenerative Ca signals, the 2+ smallest being Ca puffs, which arise from coordinated openings of a few clustered IP3Rs. 2+ Cells express thousands of mostly mobile IP3Rs, yet Ca puffs occur at a few immobile IP3R 1234567890():,; clusters. By imaging cells with endogenous IP3Rs tagged with EGFP, we show that KRas- induced actin-interacting protein (KRAP) tethers IP3Rs to actin beneath the plasma mem- brane. Loss of KRAP abolishes Ca2+ puffs and the global increases in cytosolic Ca2+ con- centration evoked by more intense stimulation. Over-expressing KRAP immobilizes additional 2+ 2+ IP3R clusters and results in more Ca puffs and larger global Ca signals. Endogenous KRAP determines which IP3Rs will respond: it tethers IP3R clusters to actin alongside sites 2+ 2+ where store-operated Ca entry occurs, licenses IP3Rs to evoke Ca puffs and global 2+ cytosolic Ca signals, implicates the actin cytoskeleton in IP3R regulation and may allow local activation of Ca2+ entry. 1 Department of Pharmacology, Tennis Court Road, Cambridge, UK. 2 Department of Basic Medical Sciences, College of Medicine, QU Health, Qatar ✉ University, Doha, Qatar. email: [email protected]; [email protected] NATURE COMMUNICATIONS | (2021) 12:4514 | https://doi.org/10.1038/s41467-021-24739-9 | www.nature.com/naturecommunications 1 ARTICLE NATURE COMMUNICATIONS | https://doi.org/10.1038/s41467-021-24739-9 2+ ytosolic Ca signals regulate diverse activities in all from EGFP-IP3R1 HeLa cells in the same ratio as their overall 1 fi eukaryotic cells .
    [Show full text]
  • Agonist-Selected T Cell Development Requires Strong T Cell Receptor Signaling and Store-Operated Calcium Entry
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Elsevier - Publisher Connector Immunity Article Agonist-Selected T Cell Development Requires Strong T Cell Receptor Signaling and Store-Operated Calcium Entry Masatsugu Oh-hora,1,2,3,4,* Noriko Komatsu,1,3 Mojgan Pishyareh,2 Stefan Feske,5 Shohei Hori,6 Masaru Taniguchi,7 Anjana Rao,2,9,* and Hiroshi Takayanagi1,3,8,10 1Department of Cell Signaling, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan 2Department of Pathology, Immune Disease Institute and Program in Cellular and Molecular Medicine, Children’s Hospital, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA 3Global Center of Excellence (GCOE) Program, International Research Center for Molecular Science in Tooth and Bone Diseases, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan 4Japan Science and Technology Agency (JST), Precursory Research for Embryonic Science and Technology (PRESTO) program, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan 5Department of Pathology, New York University, School of Medicine, New York, NY 10016, USA 6Research Unit for Immune Homeostasis 7Laboratory for Immune Regulation RIKEN Research Center for Allergy and Immunology, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan 8Japan Science and Technology Agency (JST), Explorative Research for Advanced Technology (ERATO) program, Takayanagi Osteonetwork Project, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan 9Present address: Division of Signaling and Gene Expression, La Jolla Institute for Allergy & Immunology, La Jolla, CA 92037, USA 10Present address: Department of Immunology, Graduate School of Medicine and Faculty of Medicine, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan *Correspondence: [email protected] (M.O.), [email protected] (A.R.) http://dx.doi.org/10.1016/j.immuni.2013.02.008 SUMMARY pMHC) interactions.
    [Show full text]
  • Supplementary Table S4. FGA Co-Expressed Gene List in LUAD
    Supplementary Table S4. FGA co-expressed gene list in LUAD tumors Symbol R Locus Description FGG 0.919 4q28 fibrinogen gamma chain FGL1 0.635 8p22 fibrinogen-like 1 SLC7A2 0.536 8p22 solute carrier family 7 (cationic amino acid transporter, y+ system), member 2 DUSP4 0.521 8p12-p11 dual specificity phosphatase 4 HAL 0.51 12q22-q24.1histidine ammonia-lyase PDE4D 0.499 5q12 phosphodiesterase 4D, cAMP-specific FURIN 0.497 15q26.1 furin (paired basic amino acid cleaving enzyme) CPS1 0.49 2q35 carbamoyl-phosphate synthase 1, mitochondrial TESC 0.478 12q24.22 tescalcin INHA 0.465 2q35 inhibin, alpha S100P 0.461 4p16 S100 calcium binding protein P VPS37A 0.447 8p22 vacuolar protein sorting 37 homolog A (S. cerevisiae) SLC16A14 0.447 2q36.3 solute carrier family 16, member 14 PPARGC1A 0.443 4p15.1 peroxisome proliferator-activated receptor gamma, coactivator 1 alpha SIK1 0.435 21q22.3 salt-inducible kinase 1 IRS2 0.434 13q34 insulin receptor substrate 2 RND1 0.433 12q12 Rho family GTPase 1 HGD 0.433 3q13.33 homogentisate 1,2-dioxygenase PTP4A1 0.432 6q12 protein tyrosine phosphatase type IVA, member 1 C8orf4 0.428 8p11.2 chromosome 8 open reading frame 4 DDC 0.427 7p12.2 dopa decarboxylase (aromatic L-amino acid decarboxylase) TACC2 0.427 10q26 transforming, acidic coiled-coil containing protein 2 MUC13 0.422 3q21.2 mucin 13, cell surface associated C5 0.412 9q33-q34 complement component 5 NR4A2 0.412 2q22-q23 nuclear receptor subfamily 4, group A, member 2 EYS 0.411 6q12 eyes shut homolog (Drosophila) GPX2 0.406 14q24.1 glutathione peroxidase
    [Show full text]
  • Alternative Splicing Switches STIM1 Targeting to Specialized Membrane Contact Sites and Modifies SOCE
    bioRxiv preprint doi: https://doi.org/10.1101/2020.03.25.005199; this version posted March 25, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. Alternative splicing switches STIM1 targeting to specialized membrane contact sites and modifies SOCE Mona L. Knapp1, Kathrin Förderer1, Dalia Alansary1, Martin Jung3, Yvonne Schwarz4, Annette Lis2, and Barbara A. Niemeyer1, 1Molecular Biophysics, 2Biophysics and 4Molecular Neurophysiology, Center of Integrative Physiology and Molecular Medicine (CIPMM), Bld. 48, 3Medical Biochemistry and Molecular Biology, Bld. 44, Saarland University, 66421 Homburg, Germany Alternative splicing is a potent modifier of protein function. within the first weeks 10. The early lethality indicates es- Stromal interaction molecule 1 (Stim1) is the essential activa- sential roles for Stim1 that are independent of their immune 2+ tor molecule of store-operated Ca entry (SOCE) and a sort- cell function as also indicated by the fact that also gain- ing regulator of certain ER proteins such as Stimulator of in- of-function (GOF) mutations result in multisystemic pheno- terferon genes (STING). Here, we characterize a conserved new types (see above). A mouse model expressing the STIM1 variant, Stim1A, where splice-insertion translates into an ad- gain-of-function mutation R304W, which causes Stormorken ditional C-terminal domain. We find prominent expression of syndrome in humans, also shows very few surviving off- exonA mRNA in testes, astrocytes, kidney and heart and con- firm Stim1A protein in Western blot of testes. In situ, endoge- spring with small size, abnormal bone architecture, abnor- nous Stim1 with domain A, but not Stim1 without domain A mal epithelial cell fate as well as defects in skeletal mus- 11,12 localizes to unique adhesion junctions and to specialized mem- cle, spleen and eye .
    [Show full text]
  • Intracellular Ca Signaling and Store-Operated Ca Entry Are Required in Drosophila Neurons for Flight
    Intracellular Ca2؉ signaling and store-operated Ca2؉ entry are required in Drosophila neurons for flight Gayatri Venkiteswaran and Gaiti Hasan1 National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bellary Road, Bangalore 560065, India Edited by Michael Rosbash, Brandeis University, Waltham, MA, and approved April 22, 2009 (received for review March 23, 2009) -Neuronal Ca2؉ signals can affect excitability and neural circuit for mation. Ca2؉ signals are modified by Ca2؉ flux from intracellular stores as well as the extracellular milieu. However, the contribution of intracellular Ca2؉ stores and their release to neuronal processes is poorly understood. Here, we show by neuron-specific siRNA deple- tion that activity of the recently identified store-operated channel encoded by dOrai and the endoplasmic reticulum Ca2؉ store sensor encoded by dSTIM are necessary for normal flight and associated patterns of rhythmic firing of the flight motoneurons of Drosophila melanogaster. Also, dOrai overexpression in flightless mutants for the Drosophila inositol 1,4,5-trisphosphate receptor (InsP3R) can par- tially compensate for their loss of flight. Ca2؉ measurements show that Orai gain-of-function contributes to the quanta of Ca2؉-release 2؉ through mutant InsP3Rs and elevates store-operated Ca entry in Drosophila neurons. Our data show that replenishment of intracel- .lular store Ca2؉ in neurons is required for Drosophila flight calcium homeostasis ͉ flight patterns ͉ inositol 1,4,5-trisphosphate receptor ͉ sarco-endoplasmic reticulum-associated Ca2ϩ ATPase ͉ STIM everal aspects of neuronal function are regulated by ionic Scalcium (Ca2ϩ). Specific attributes of a Ca2ϩ‘‘signature’’ such as amplitude, duration, and frequency of the signal can determine the morphology of a neural circuit by affecting the outcome of cell migration, the direction taken by a growth-cone, dendritic devel- opment, and synaptogenesis (1).
    [Show full text]
  • Calmodulin Binding Proteins and Alzheimer's Disease
    International Journal of Molecular Sciences Review Calmodulin Binding Proteins and Alzheimer’s Disease: Biomarkers, Regulatory Enzymes and Receptors That Are Regulated by Calmodulin Danton H. O’Day 1,2 1 Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada; [email protected] 2 Department of Biology, University of Toronto Mississauga, Mississauga, ON L5L 1C6, Canada Received: 18 September 2020; Accepted: 3 October 2020; Published: 5 October 2020 Abstract: The integral role of calmodulin in the amyloid pathway and neurofibrillary tangle formation in Alzheimer’s disease was first established leading to the “Calmodulin Hypothesis”. Continued research has extended our insight into the central function of the small calcium sensor and effector calmodulin and its target proteins in a multitude of other events associated with the onset and progression of this devastating neurodegenerative disease. Calmodulin’s involvement in the contrasting roles of calcium/CaM-dependent kinase II (CaMKII) and calcineurin (CaN) in long term potentiation and depression, respectively, and memory impairment and neurodegeneration are updated. The functions of the proposed neuronal biomarker neurogranin, a calmodulin binding protein also involved in long term potentiation and depression, is detailed. In addition, new discoveries into calmodulin’s role in regulating glutamate receptors (mGluR, NMDAR) are overviewed. The interplay between calmodulin and amyloid beta in the regulation of PMCA and ryanodine receptors are prime examples of how the buildup of classic biomarkers can underly the signs and symptoms of Alzheimer’s. The role of calmodulin in the function of stromal interaction molecule 2 (STIM2) and adenosine A2A receptor, two other proteins linked to neurodegenerative events, is discussed.
    [Show full text]
  • STIM1 Phosphorylation at Y361 Recruits Orai1 to STIM1 Puncta And
    www.nature.com/scientificreports OPEN STIM1 Phosphorylation at Y361 Recruits Orai1 to STIM1 Puncta and Induces Ca2+ Entry Received: 05 December 2016 Pascal Yazbeck1, Mohammad Tauseef1,2, Kevin Kruse1, Md-Ruhul Amin1, Rayees Sheikh1, Accepted: 12 January 2017 Stefan Feske3, Yulia Komarova1 & Dolly Mehta1 Published: 20 February 2017 Store-operated Ca2+ entry (SOCE) mediates the increase in intracellular calcium (Ca2+) in endothelial cells (ECs) that regulates several EC functions including tissue-fluid homeostasis. Stromal-interaction molecule 1 (STIM1), upon sensing the depletion of (Ca2+) from the endoplasmic reticulum (ER) store, organizes as puncta that trigger store-operated Ca2+ entry (SOCE) via plasmalemmal Ca2+- selective Orai1 channels. While the STIM1 and Orai1 binding interfaces have been mapped, signaling mechanisms activating STIM1 recruitment of Orai1 and STIM1-Orai1 interaction remains enigmatic. Here, we show that ER Ca2+-store depletion rapidly induces STIM1 phosphorylation at Y361 via proline- rich kinase 2 (Pyk2) in ECs. Surprisingly, the phospho-defective STIM1-Y361F mutant formed puncta but failed to recruit Orai1, thereby preventing. SOCE Furthermore, studies in mouse lungs, expression of phosphodefective STIM1-Y361F mutant in ECs prevented the increase in vascular permeability induced by the thrombin receptor, protease activated receptor 1 (PAR1). Hence, Pyk2-dependent phosphorylation of STIM1 at Y361 is a critical phospho-switch enabling recruitment of Orai1 into STIM1 puncta leading to SOCE. Therefore, Y361 in STIM1 represents a novel target for limiting SOCE- associated vascular leak. Endothelial barrier function is vital in the regulation of tissue-fluid homeostasis, angiogenesis, and inflammation1,2. Loss of endothelial barrier function following burn, trauma, or sepsis leads to acute lung injury (ALI), a life threatening condition due to respiratory failure3,4.
    [Show full text]
  • Stims and Orai1 Regulate Cytokine Production in Spinal Astrocytes Xinghua Gao1,2, Jingsheng Xia1, Frances M
    Gao et al. Journal of Neuroinflammation (2016) 13:126 DOI 10.1186/s12974-016-0594-7 RESEARCH Open Access STIMs and Orai1 regulate cytokine production in spinal astrocytes Xinghua Gao1,2, Jingsheng Xia1, Frances M. Munoz1, Melissa T. Manners1, Rong Pan1, Olimpia Meucci1, Yue Dai2 and Huijuan Hu1* Abstract Background: Our previous study demonstrated that a store-operated calcium channel (SOCC) inhibitor (YM-58483) has central analgesic effects. However, the cellular and molecular mechanisms of such effects remain to be determined. It is well-known that glial cells play important roles in central sensitization. SOC entry (SOCE) has been implicated in many cell types including cortical astrocytes. However, the role of the SOCC family in the function of astrocytes has not been determined. Here, we thoroughly investigated the expression and the functional significance of SOCCs in spinal astrocytes. Methods: Primary cultured astrocytes were prepared from neonatal (P2–P3) CD1 mice. Expressions of mRNAs and proteins were respectively assessed by real-time PCR and Western blot analysis. SOCE was measured using a calcium imaging system. Live-cell STIM1 translocation was detected using a confocal microscope. Cytokine levels were measured by the enzyme-linked immunosorbent assay. Results: We found that the SOCC family is expressed in spinal astrocytes and that depletion of calcium stores from the endoplasmic reticulum by cyclopiazonic acid (CPA) resulted in a large sustained calcium entry, which was blocked by SOCC inhibitors. Using the siRNA knockdown approach, we identified STIM1 and Orai1 as primary components of SOCCs in spinal astrocytes. We also observed thapsigargin (TG)- or CPA-induced puncta formation of STIM1 and Orai1.
    [Show full text]